It has recently become common practice to record video and audio data obtained by shooting in such a way that they are incorporated with additional information for their editing. (See, for example, Japanese Patent Laid-open No. 2001-292421, pp. 14-15, FIG. 8.)
The additional information may be metadata such as LTC (Linear Time Code), which is recorded in a recording medium together with the video and audio data. The editor uses this LTC for editing, thereby searching video and audio data, synthesizing several clips into one cut, and determining the timing (frame) to join clips together. In this case, the result of the editing of video and audio data is the edit list which is controlled as a file separate from the original clip data.
In other words, the editing of video and audio data yields the bridge essence file which is information resulting from the editing of individual pieces of data. The bridge essence file functions as the edit list which is controlled for individual edit units. The bridge essence file is a file to reproduce the video and audio data of original clips according to the content of the edit list (which is the result of editing), and hence it contains information about the procedure for reproduction. Thus the edit list permits the user to reproduce the result of editing of video and audio data. In other words, the edit list permits the user to carry out the (non-destructive) editing work without updating the video and audio data in the original clips.
In the above-mentioned procedure, however, the LTC is processed in the same way as the video and audio data. A problem in this situation is that when one cut is produced from several clips, it is difficult to unify the LTC in that cut. For example, if the user is to produce one cut from several clips containing mutually independent LTCs, he has to do the following to unify the LTCs after editing. That is, the user adds the LTC to the clips by foreseeing their synthesis, or the user rewrites directly the LTC data contained in the original several clips.
Thus, the above-mentioned procedure would be inconvenient in the case where the user wants to carry out (non-destructive) editing, such as synthesis of clips, without affecting data in the original clips.
If there exist a plurality of clips corresponding to the results of each editing, then there exist also a plurality of files of metadata containing LTC because LTC is produced for each clip. Thus, if video and audio data are to be read by using the edit list, it is also necessary to read the file of metadata containing LTCs. The disadvantage of the procedure mentioned above is that it takes a long time with an increased load to reproduce video and audio data based on the results of editing.